Preheat oven to 400º F.
Slice a small piece off the top and bottom of the acorn squash to allow it to sit evenly without rolling. Then, cut the acorn squash in half, remove seeds and brush the edible portion of the squash with olive oil.
Place the prepared squash, oiled (flesh) side down on a parchment lined baking sheet. Roast in the preheated oven until fork-tender, approximately 25 - 30 minutes.
Meanwhile, brown the sausage with the onion and bell pepper in a large skillet over medium high heat, crumbling and breaking meat while stirring.
Drain any excess fat then add the Bertolli® Marinara Sauce and cook until heated through, approximately 3 minutes. Remove from heat and stir in half of the parmesan cheese.
Once the squash is tender, use tongs to flip so that the bowl-side of the squash is upright.
Divide the filling and spoon into the prepared squash, piling the meat mixture high.
Sprinkle with the remaining parmesan cheese and broil for 2 - 3 minutes, until melted.
Garnish with additional cheese and chopped parsley, if desired.